Index: channels/chan_sip.c
===================================================================
--- channels/chan_sip.c	(revision 110639)
+++ channels/chan_sip.c	(working copy)
@@ -780,7 +780,7 @@
 	ast_mutex_t *lock;
 	enum sip_transport type;
 	int fd;
-	uint16_t port;
+	uint16_t port; /* XXX Is this even used anywhere? */
 	struct ast_tcptls_session_instance *ser;
 };
 
@@ -18225,22 +18225,49 @@
 	struct sip_socket *s = &p->socket;
 	static const char name[] = "SIP socket";
 	struct ast_tcptls_session_instance *ser;
+	struct sip_threadinfo *thread;
 	struct server_args ca = {
 		.name = name,
 		.accept_fd = -1,
 	};
+	int deadthread = 0; /* boolean used to see if we just killed a TCP helper thread */
 
-	if (s->fd != -1)
-		return s->fd;
+	ca.sin = *(sip_real_dst(p));
 
+	if (s->fd != -1) {
+		if ((s->type & SIP_TRANSPORT_TCP) && s->ser && inaddrcmp(&s->ser->requestor, &ca.sin)) {
+			/* Let's stop the previously running helper thread associated with this
+			 * socket.
+			 */
+			AST_LIST_LOCK(&threadl);
+			AST_LIST_TRAVERSE(&threadl, thread, list) {
+				if (thread->ser->fd == s->fd) { /* XXX Specific enough check ? */
+					/* This will signal the thread to stop */
+					thread->stop = 1;
+					/* This will wake it from the poll if necessary */
+					pthread_kill(thread->threadid, SIGURG);
+					deadthread = 1;
+				}
+			}
+			AST_LIST_UNLOCK(&threadl);
+			/* XXX Is this enough? The cleanup section of the tcp helper thread
+			 * closes fd's, but I don't know if it's enough to actually shut down
+			 * the TCP connection
+			 */
+		} else {
+			return s->fd;
+		}
+	}
+
 	if (s->type & SIP_TRANSPORT_UDP) {
 		s->fd = sipsock;
 		return s->fd;
 	}
 
-	ca.sin = *(sip_real_dst(p));
-
-	if ((ser = sip_tcp_locate(&ca.sin))) {
+	/* No point searching for the associated tcp helper thread if
+	 * we just killed it
+	 */
+	if (!deadthread && (ser = sip_tcp_locate(&ca.sin))) {
 		s->fd = ser->fd;
 		s->ser = ser;
 		return s->fd;